This could be only Curbing or Normal. However, if I try to sing it in Curbing it sounds either too strained/holden up or too powerful, and if I try Normal it is just a bit too breathy/weak - the difference from the rest of the phrase is too obvious.

Josh Groban is baritone, and so am I... so it's probably not natural for him to sing F4 so midly too. Maybe that is due to his operatic, or almost operatic training?

Of course, he is a master so I am not comparing anything, just striving